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SIGHT & LIGHT demo in Python/PyGame

View sightandlight.py
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'''
SIGHT & LIGHT by ncase (https://github.com/ncase/sight-and-light)
Ported to Python/PyGame by Marcus Møller (https://github.com/marcusmoller)
'''
 
import pygame
import pygame.gfxdraw
import math
 
class SightAndLight():
def __init__(self):
# initialize pygame
pygame.init()
self.screen = pygame.display.set_mode((640, 360))
pygame.display.set_caption("SIGHT & LIGHT Demo - Python/PyGame")
 
# mouse position
self.mouse_pos = (0, 0)
 
# general
self.fps_clock = pygame.time.Clock()
self.running = True
self.update_shadows = True # only call update on mouse movement
 
# segments
self.segments = [
# Border
{"a":{"x":0,"y":0}, "b":{"x":640,"y":0}},
{"a":{"x":640,"y":0}, "b":{"x":640,"y":360}},
{"a":{"x":640,"y":360}, "b":{"x":0,"y":360}},
{"a":{"x":0,"y":360}, "b":{"x":0,"y":0}},
 
# Polygon #1
{"a":{"x":100,"y":150}, "b":{"x":120,"y":50}},
{"a":{"x":120,"y":50}, "b":{"x":200,"y":80}},
{"a":{"x":200,"y":80}, "b":{"x":140,"y":210}},
{"a":{"x":140,"y":210}, "b":{"x":100,"y":150}},
 
# Polygon #2
{"a":{"x":100,"y":200}, "b":{"x":120,"y":250}},
{"a":{"x":120,"y":250}, "b":{"x":60,"y":300}},
{"a":{"x":60,"y":300}, "b":{"x":100,"y":200}},
 
# Polygon #3
{"a":{"x":200,"y":260}, "b":{"x":220,"y":150}},
{"a":{"x":220,"y":150}, "b":{"x":300,"y":200}},
{"a":{"x":300,"y":200}, "b":{"x":350,"y":320}},
{"a":{"x":350,"y":320}, "b":{"x":200,"y":260}},
 
# Polygon #4
{"a":{"x":340,"y":60}, "b":{"x":360,"y":40}},
{"a":{"x":360,"y":40}, "b":{"x":370,"y":70}},
{"a":{"x":370,"y":70}, "b":{"x":340,"y":60}},
 
# Polygon #5
{"a":{"x":450,"y":190}, "b":{"x":560,"y":170}},
{"a":{"x":560,"y":170}, "b":{"x":540,"y":270}},
{"a":{"x":540,"y":270}, "b":{"x":430,"y":290}},
{"a":{"x":430,"y":290}, "b":{"x":450,"y":190}},
 
# Polygon #6
{"a":{"x":400,"y":95}, "b":{"x":580,"y":50}},
{"a":{"x":580,"y":50}, "b":{"x":480,"y":150}},
{"a":{"x":480,"y":150}, "b":{"x":400,"y":95}}
]
 
# Intersects
self.intersects = []
 
# Points
self.points = []
 
def run(self):
while self.running:
self.main_loop()
 
def main_loop(self):
self.handle_input()
if self.update_shadows:
self.update()
self.update_shadows = False
self.render_frame()
 
 
def update(self):
# Clear old points
self.points = []
 
# Get all unique points
for segment in self.segments:
self.points.append((segment['a'], segment['b']))
 
unique_points = []
for point in self.points:
if point not in unique_points:
unique_points.append(point)
 
# Get all angles
unique_angles = []
for point in unique_points:
angle = math.atan2(point[0]["y"]-self.mouse_pos[1], point[0]["x"]-self.mouse_pos[0])
point[0]["angle"] = angle
unique_angles.append(angle-0.00001)
unique_angles.append(angle)
unique_angles.append(angle+0.00001)
 
# RAYS IN ALL DIRECTIONS
self.intersects = []
for angle in unique_angles:
# Calculate dx & dy from angle
dx = math.cos(angle)
dy = math.sin(angle)
 
# Ray from center of screen to mouse
ray = {
"a": {"x":self.mouse_pos[0], "y": self.mouse_pos[1]},
"b": {"x": self.mouse_pos[0]+dx, "y": self.mouse_pos[1]+dy}
}
 
# Find CLOSEST intersection
closest_intersect = None
for segment in self.segments:
intersect = self.get_intersection(ray, segment)
if not intersect: continue
if not closest_intersect or intersect["param"] < closest_intersect["param"]:
closest_intersect = intersect
 
# Intersect angle
if not closest_intersect: continue
closest_intersect["angle"] = angle
 
# Add to list of intersects
self.intersects.append(closest_intersect)
 
# Sort intersects by angle
self.intersects = sorted(self.intersects, key=lambda k: k['angle'])
 
def render_frame(self):
self.screen.fill((255, 255, 255))
 
# draw segments
for segment in self.segments:
pygame.draw.aaline(self.screen, (153, 153, 153), (segment['a']['x'], segment['a']['y']), (segment['b']['x'], segment['b']['y']))
 
self.draw_polygon(self.intersects, (221, 56, 56))
 
# draw debug lines
for intersect in self.intersects:
pygame.draw.aaline(self.screen, (255, 85, 85), self.mouse_pos, (intersect['x'], intersect['y']))
 
# limit fps
self.fps_clock.tick(60)
 
# update screen
pygame.display.update()
 
def handle_input(self):
pygame.event.pump()
for event in pygame.event.get():
if event.type == pygame.QUIT:
self.running = False
print("quit")
break
 
# KEYBOARD
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_ESCAPE or event.key == pygame.K_q:
self.running = False
 
# MOUSE
elif event.type == pygame.MOUSEMOTION:
self.mouse_pos = event.pos
self.update_shadows = True
 
def get_intersection(self, ray, segment):
''' Find intersection of RAY & SEGMENT '''
# RAY in parametric: Point + Direction*T1
r_px = ray['a']['x']
r_py = ray['a']['y']
r_dx = ray['b']['x'] - ray['a']['x']
r_dy = ray['b']['y'] - ray['a']['y']
 
# SEGMENT in parametric: Point + Direction*T2
s_px = segment['a']['x']
s_py = segment['a']['y']
s_dx = segment['b']['x'] - segment['a']['x']
s_dy = segment['b']['y'] - segment['a']['y']
 
# Are they parallel? If so, no intersect
r_mag = math.sqrt(r_dx*r_dx+r_dy*r_dy)
s_mag = math.sqrt(s_dx*s_dx+s_dy*s_dy)
if r_dx/r_mag == s_dx/s_mag and r_dy/r_mag == s_dy/s_mag:
return None
 
# SOLVE FOR T1 & T2
# r_px+r_dx*T1 = s_px+s_dx*T2 && r_py+r_dy*T1 = s_py+s_dy*T2
# ==> T1 = (s_px+s_dx*T2-r_px)/r_dx = (s_py+s_dy*T2-r_py)/r_dy
# ==> s_px*r_dy + s_dx*T2*r_dy - r_px*r_dy = s_py*r_dx + s_dy*T2*r_dx - r_py*r_dx
# ==> T2 = (r_dx*(s_py-r_py) + r_dy*(r_px-s_px))/(s_dx*r_dy - s_dy*r_dx)
 
# todo: fix zerodivision error handling
try:
T2 = (r_dx*(s_py-r_py) + r_dy*(r_px-s_px))/(s_dx*r_dy - s_dy*r_dx)
except ZeroDivisionError:
T2 = (r_dx*(s_py-r_py) + r_dy*(r_px-s_px))/(s_dx*r_dy - s_dy*r_dx-0.01)
 
try:
T1 = (s_px+s_dx*T2-r_px)/r_dx
except ZeroDivisionError:
T1 = (s_px+s_dx*T2-r_px)/(r_dx-0.01)
 
# Must be within parametic whatevers for RAY/SEGMENT
if T1 < 0: return None
if T2 < 0 or T2>1: return None
 
# Return the POINT OF INTERSECTION
return {
"x": r_px+r_dx*T1,
"y": r_py+r_dy*T1,
"param": T1
}
 
def draw_polygon(self, polygon, color):
# collect coordinates for a giant polygon
points = []
for intersect in polygon:
points.append((intersect['x'], intersect['y']))
# draw as a giant polygon
pygame.gfxdraw.aapolygon(self.screen, points, color)
pygame.gfxdraw.filled_polygon(self.screen, points, color)
 
if __name__ == "__main__":
demo = SightAndLight()
demo.run()
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